Same issue with IVTV 0.8.1.
I don't think it's DMA but I could be wrong. WHILE recording on 1
tuner, and playing another video on the frontend (FE and BE are the
same machine), I can still obtain this:
tv1 ~ # hdparm -tT /dev/md2
/dev/md2:
Timing cached reads: 1184 MB in 2.01 seconds = 589.36 MB/sec
Timing buffered disk reads: 92 MB in 3.21 seconds = 28.62 MB/sec
I have noticed that is doesn't happen ALL the time, but 80% to 90% of
it. It has really jacked up trying to process any of the video
externally, and watching the video jacks the A/V sync. My
installation has worked great since it's first install in March and
now I don't know what to do.
Any other ideas? Check it out... 7 seconds in.
http://www.youtube.com/watch?v=TC8qiowyGfw